On 2019/10/9 17:48, James Clark wrote: > Hi Xiaojun, > >> By the way, you mentioned before that you want the spe event to be in the >> form of "event:pp" like pebs. Is that the whole framework should be made >> similar to pebs? Or is it just a modification to the command format? > > We're currently still investigating if it makes sense to modify the Perf > event open syscall to use SPE when the "precise_ip" attribute is set. And > then synthesize samples using the SPE data when available. This would keep > the syscall interface more consistent between architectures. > > And if tools other than Perf want more precise data, they don't have to be > aware of SPE or any of the implementation defined details of it. For example > the 'data source' encoding can be different from one micro architecture to > the next. The kernel is probably the best place to handle this. > > At the moment, every tool that wants to use the Perf syscall to get precise > data on ARM would have to be aware of SPE and implement their own decoding. >
Hi James, What do you mean when the user specifies "event:pp", if the SPE is available, configure and record the spe data directly via the perf event open syscall? (perf.data itself is the same as using -e arm_spe_0//xxx?) OK. If I have not misunderstood, I think I know how to do it. Thank you. >> For the former, this may be a bit difficult. For the latter, there is >> currently no modification to the record part, so "-c -F, etc." is only for >> instructions rather than events, so it may be misunderstood by users. >> >> So I haven't figured out how to do. What do you think of this? > > I think the patch at the moment is a good start to make SPE more accessible. > And the changes I mentioned above wouldn't change the fact that the raw SPE > data would still be available via the SPE PMU. So I think continuing with the > patch as-is for now is the best idea. > Yes. I agree. Xiaojun. > > James > >
